Airborne particulates, such as fine dust, dirt, sand, crop material, and the like, must be separated from air entering an internal combustion engine such that the particulates do not travel on to clog passages within the engine and/or cause significant damage thereto. A well known manner of separating such particulates from the air flow is to cause the air to flow in a vortex or cyclone stream such that airborne particulates can be deflected or directed out of the air flow which travels onto the engine. Reference in this regard, Roach et al. U.S. Pat. No. 3,915,679, issued Oct. 28, 1975 to Pall Corporation; and Sundseth U.S. Pat. No. 4,394,145, issued Jul. 19, 1993, which disclose air cleaners or air pre-cleaners utilizing a plurality of tubular dust or particle separator elements arranged in an array in a housing and within which the particles of dust and the like are separated from air flowing therethrough enroute to an engine or other device. The Roach et al. patent is further noted as it discloses an outlet line connection from the air cleaner array to a blower operable for scavenging air flow from the array to carry away and remove the dirt separated from a main air flow to the engine, the outlet line connection being located beneath the array. A disadvantage of dust disposal arrangements such as that of the Roach et al. patent is the requirement of the blower, which adds expense and complexity, takes power from the engine, and any failure or inadequate operation of which can have severe operational consequences. The Sundseth patent, in contrast, discloses a simpler elastomeric dust valve member which collects the dust and discharges it when the weight thereof overcomes elastic sealing valve lips of the valve member. A shortcoming of this manner of disposal, however, is the evident limited dust disposal capacity and thus a resultant lack of utility for extremely dusty applications as can be encountered such as for use on agricultural harvesting machines such as combines and cotton pickers, which are known to be used in environments so dusty that visibility around the combine or picker is near zero.
Still other known pre-cleaner constructions utilize exhaust flow of the engine for aspirating or scavenging dust and other particulates from the pre-cleaner housing, such as disclosed in Lidstone et al. U.S. Pat. No. 4,218,223, issued Aug. 19, 1980 to Donaldson Company, Inc., which advantageously eliminates the need for a blower. However, a shortcoming possible with devices of this type is that the port connected to the exhaust for aspirating or scavenging the collected dust is located and oriented so as to be possibly less effective for removing dust from the device during and after periods of low exhaust flow conditions, such as when the engine is idling or operating under a low load, resulting in an accumulation of the dust or other particulates in the lower region of the device so as to require more frequent cleaning of the device, which can be time-consuming and costly.
Thus what is sought is an aspiration type pre-cleaner for the air intake or induction path of an internal combustion engine which provides an effective particulate separation capability without requiring the complexity of a blowers or the like, and which is less prone to particulate build-up and blockage brought on as a result of periods of idle, low engine load operation, and the like.